SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3864129f404b559468de75c42919901eee481221d0c8941893cb61b3b710571a' 
  AND token = 'swtq/019pajYCX1ssxcEDHPACXr73UL4XBA2K8/AZBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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