SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cea9ac76ed8688320751761703c163325b4b6cab51f51704d61090f4ad2f519' 
  AND token = 'yjzRRtaDDEjAk6rEZFXMo3MuwpSoYx24i+mGqbxXekg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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