SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f0d0639d0ff5a1978326cfc6690ec5ceacdab5bb2c08da65113b0114921f67' 
  AND token = 'Zg0unN4QXVX8mGU+2tLJQDGczIbt1AnKhn3AwpL8YGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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