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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eab044780d6037ee3e5e58551e900995613d41e51805287ccfca14612f571fa' 
  AND token = 'KFiaL7bamdJYpUVx1AkcVdndgDtlQXlglzYkFABMMQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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