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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c08ee9cded47376a0e144f4063a4b0481ed4ae5ae06b7ca721fa8c7fc51d6b' 
  AND token = 'z2Z2HokbQz+q7JLe9NBlUK0tp4GRZyTt9sNpCNkZwM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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