SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d8aa4d0e0441b2bc1bcc121b23075d556e3a8e17ad3e1da88866067fc2578be' 
  AND token = 'b4Nm7RCOgUaHEqSmGPcy3uJv4Gx+ULutvCohfvlhVfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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