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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd38ca2d16435888d2d5e6f00b48c59d4c5cbd2ccdad4a4bb3c30afce3a568a4d' 
  AND token = 'VS1tVDyx2C96FZbIE4LbrysButfaZRuuCqE1nS8CCuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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