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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b645f83263202fe48519c3e36e45ac9bc6b0adefadeb04a572882a14ef7edc74' 
  AND token = 'AYixaTffuImPF+WhMZFiFJtkFgxanO+hB030KIf/nSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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