SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6e6238e473f1340cd06cf52137ea839f33ecdcb60cf6635600e84d741a9ea1d' 
  AND token = 'VxsG9mKOslZ1fEr/F3YsNKZWz3AwkXhrGtdpAwgCTjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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