SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51026b67c59ddfe8709d08b77db2531e6000a1ad4296f088fbdcbbfd426cd76c' 
  AND token = 'zEqgCH01C00ItL2cDrnO0fQ7qvpzVrOH5kBRrpCTHiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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