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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffca5d54b4d463b85945f993b8a9d79f0e97c6e0b5065cdfda5d1009abf9bff6' 
  AND token = '4QmgU+hekE4LmRkqoBJFx1msN5HMjq2q4rS6IQDxv+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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