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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1498e29302128984a4c0f2eed5a53873d6202474aa80d64fde771d4f9daa6ff2' 
  AND token = 'e6z8DoLarF8PdGAfJ17sFPZ3ezy4ucJ/PTmB8pYM8QE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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