SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '422d309b950f1e8074e3648fadd20354c7ed4ec49888306a9162c21f19251fc3' 
  AND token = 'bOkYJmDP9CiSHCL7PW3DuwS0IDF+yMzIjRHXvPmRDk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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