SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de8c2085b3be9787b2ed2cacf1147e82c9589f7cbf3e3d43fd2e51c164bfa2a4' 
  AND token = 'ELj7MsGgYJkJtVmA1YC+drF7o327LZ0A49qGTs3a4xs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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