SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e928d8ed0895f6194f826c9178dfcf84566540facf361f478e1f2a86e36b2dd7' 
  AND token = 'xDvJ70yo4+Be5cVSZzpzRLebg30Rny8yTocAQsKqkKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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