SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '57b3cf0e26c275430df55d19a9945f520a489dd17984ef2efdb1a0cf8bca873e' 
  AND token = 'xhi2CYSPdwZ+MyR8Ad7qXSOWb2tW3JjOQTAo4GPRDmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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