SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c84be3c2603cd82d5c06fad52204cdef4b320259f5350e20de030bbabff2d87b' 
  AND token = 'scJX29eRKh3ot17UYvUJWBgECkFPLaUhxnuEfeqZEAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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