SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17083ce8c2c65e24806ffb850842c2da2acb11438b971fffdbfd2e4f9786941c' 
  AND token = 'liWc8hmheA2kExcwsgQ8WoRhcciW+ltCMfAQ12GWIcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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