SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '2014b66fcefa53375fbe147104421bca27b7c934adc8d17c17981702afb345f2' 
  AND token = 'cx2EOnnJf9jBFGfsACn2cwcEioO5O+fIDZCZCTWlj/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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