SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0cff706ab5466a34f211de9fa867b936e5eb3dab10e1c91d68823340d590327' 
  AND token = 't4ic32ZJzhgtsiXQOrwAw4e+4wSil2uGWj3qUtycgG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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