SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb085512ff3361acbe0905923967c933f54ff83d1f8f5b054cdf19852d1297f3' 
  AND token = 'JgO8SHobw3jiF85cl/21WyxBSkzH8UcD7MtkcgtjayI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}