SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1c6b08885511c7ad6bcf6949e334fd09ca4a8374166be6ad4b11cfbda44e38b' 
  AND token = 'PYhX3heg9S1rQk/ymrDqMx2LBXflejaPsH3gK6PtdAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00098

JSON explain

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