SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73b3ee390b130203a9fafe3a007458d46521ba8db0c6840a39fce99c9201bb9d' 
  AND token = 'Pjv80f+d2YnnyUNrTyy69KRTbrmpZtHtSiIimtP2v4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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