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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c992a0f983cea7c5e191337cd90cfc61b61bc7fe81fa8c5120f29aa1396902f0' 
  AND token = 'b4VGqJMfZbgIqNZ1XKxxKu6/qz2i3+wZS5nKFQ16Lpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}