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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f75d7c1a82119b751475d649f0ccb7ace8da5e3fd4a6bc3dd1188ccddcc5e50d' 
  AND token = 'LL9xhqlu+USN4KTRqXN3TK56+KEsGdHyhHUQDuS61l8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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